I believe a good writer can write a good book with any sort of character, in any sort of setting, but I prefer to write about the outsider. It might just be because I've been one (or perceived myself to be one) for so much of my life. But the simple fact of being marginalized immediately brings conflict to a story before the narrative even begins, and that's gold for a writer because it means that your character already has depth before events begin to unfold.